RF1238B
•
•
•
•
Ideal Front-End Filter for European Wireless Receivers
Low-Loss, Coupled-Resonator Quartz Design
Simple External Impedance Matching
Surface-Mount Ceramic Case with 52 mm
2
Footprint
318.0 MHz
SAW Filter
The RF1238B is a low-loss, compact, and economical surface-acoustic-wave (SAW) filter designed to pro-
vide front-end selectivity in 318.0 MHz receivers. Receiver designs using this filter include superhet with
10.7 MHz or 500 kHz IF, direct conversion and superregen. Typical applications of these receivers are wire-
less remote-control and security devices operating in the USA under FCC Part 15, in Canada under DOC
RSS210, and in Australia.
This coupled-resonator filter (CRF) uses selective null placement to provide suppression, typically greater
than 40 dB, of the LO and image spurious responses of superhet receivers with 10.7 MHz IF. RFM’s ad-
vanced SAW design and fabrication technology is utilized to achieve high performance and very low loss with
simple external impedance matching (not included). Our new patent pending solder seal process utilizes a
Faraday shield lid, which improves out of band rejection.
SM8558-8 Case
Electrical Characteristics
Characteristic
Nominal Frequency
Insertion Loss
3 dB Passband
3 dB Rejectband
Rejection
at f
c
- 21.4 MHz (Image)
at f
c
- 10.7 MHz (LO)
Ultimate
Temperature
Operating Case Temp.
Turnover Temperature
Turnover Frequency
Freq. Temp. Coefficient
Frequency Aging
External Impedance
Absolute Value during the First Year
Series Inductance
Shunt Capacitance
Lid Symbolization (in addition to Lot and/or Date Codes)
T
C
T
O
f
O
FTC
|fA|
L
C
3
1, 7
3, 7, 8
-40
15
25
f
C
0.032
<±10
47
5-18
RF1238B
4
Sym
f
C
IL
BW
3
BW
3
Notes
2, 4, 5, 6
3, 4, 7
2, 3, 4, 7
2, 3, 4, 7
40
15
±135
50
30
80
+85
40
°C
°C
MHz
ppm/°C
2
ppm/yr
nH
pF
dB
Minimum
Typical
318.00
5.0
8.5
Maximum
Units
MHz
dB
kHz
kHz
CAUTION: Electrostatic Sensitive Device. Observe precautions for handling.
Notes:
1. Typical demonstration circuit shown is for SM8558-8 solder seal filters.
2. Passband and reject bands are specified in reference to f
c
.
3. All characteristics are specified over the operating temperature range and typical aging is 10 years.
4. Unless noted otherwise, all measurements are made with the filter installed in the specified test fixture. Note that insertions loss, bandwidth, and
passband shape are dependent on the impedance matching component values and quality. Demonstration circuits are available for confirmation of
device performance.
5. One or more of the following U.S. Patents apply: 4,454,488; 4,616,197; and others pending.
6. All equipment designs utilizing this product must be approved by the appropriate government agency prior to manufacture or sale.
7. The design, manufacturing process, and specifications of this device are subject to change without notice.
8. The turnover temperature, TO, is the temperature of maximum (or turnover) frequency, f
o
. The nominal frequency at any case temperature, T
c
, out-
side the operating temperature range may be calculated from: f = f
o
[1 - FTC (T
o
- T
c
)
2
].
RF Monolithics, Inc.
Phone: (972) 233-2903
Fax: (972) 387-9148
RFM Europe
Phone: 44 1963 251383
Fax: 44 1963 251510
©1999 by RF Monolithics, Inc. The stylized RFM logo are registered trademarks of RF Monolithics, Inc.
E-mail: info@rfm.com
http://www.rfm.com
RF1238B-101599
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RFM [ RF MONOLITHICS, INC ]
